Workflow is among the most highly investigated problems in distributed computing and many complete workflow systems exist. However, these workflow systems execute jobs in a homogeneous way. For example, BPEL4WS is a workflow specification for orchestrating Web Service invocations in order to realize a workflow. IBM's LoadLeveler is a high performance computing job scheduler that can orchestrate workflows running on clusters of machines connected by a network. Lotus Workflow is a system for orchestrating workflow where the jobs are performed by user applications on personal workstations and orchestrated via a document management system.
Although useful, these workflow systems are not without their deficiencies, drawbacks, and problems. For example, these workflow systems cannot orchestrate workflow where the job steps involved are high performance computing applications, web services, and user applications. In addition, advanced fields such as Cancer research require workflows involving the participation of laboratory equipment.
Workflow systems sometimes provide user interfaces for user interaction with the workflow. However, these user interfaces are often difficult to use when trying to find compatible input and output parameters for workflow steps. For example, in a semantic data application, where a data object in the system might represent any number of different semantic data types, it is not always possible for a user to easily determine which parts of an application can provide and or accept the data objects when they are involved in a drag and drop operation. Current user interfaces utilizing drag and drop features, show a user which parts of the application can accept or provide a data object by changing the mouse icon when the a data object is dragged over different parts of the application. The drawback of this type of system, is that the user must first drag the data object to all possible parts of an application to determine which parts of the application are valid receptors of the drag and drop operation.
Therefore a need exists to overcome the problems with the prior art as discussed above.